The discovery was made around 1:00 p.m. Tuesday by a man fishing at Corson's Inlet State Park.
Investigators say the man found a sneaker with skeletal remains inside of it.
The medical examiner said the remains are of a right foot inside a black Adidas ADI Rise 2 high-top sneaker, size 5½.
Some of the toes have colored nail polish, but the gender and age are unknown.
Police say the remains will be sent to the State Anthropologist for examination and DNA testing.
Anyone with information is asked to contact the New Jersey State Police Major Crime Unit at (609) 561-1800 ext. 3355.